Tetracyclines are broad-spectrum antibiotics, indicated for use against many bacterial infections. Although widely utilized their use has been associated with intrinsic staining of human teeth (especially in children), bones, and soft tissues. This staining has been recognized as being due to an oxidation reaction.
Laboratory studies have shown that the pigment formation can be induced by exposure to ultraviolet light in the presence of air. Animal studies, in rats, have established that simultaneous administration of ascorbic acid (vitamin C) with minocycline prevented staining of the teeth and bones and pigmentation of the thyroid gland (see “Bowles W H, Protection against minocycline pigment formation by ascorbic acid (vitamin C), J. Esthet. Dent. 1998; 10(4): 182-6”).
In order to solve the problem of tetracycline induced staining of human teeth, bones and soft tissues; we have now developed a concept for co-administration of a tetracycline and an antioxidant by means of combining, in a particle, the tetracycline or one of its pharmaceutically acceptable salts and an antioxidant. The proportions of the tetracycline and antioxidant can be varied over a wide range and are not limited by any particular physical or chemical constraint. For example, it is envisaged that the particle may comprise from 90% w/w tetracycline/10% w/w antioxidant to 10% w/w tetracycline/90% w/w antioxidant.